[Antigone]

This is basic and most-common terms used. Please learn them as it serves as common knowledge in RPGs.

Mary Sue/Gary Stu - An unrealistically perfect character, typically female. Has no major flaws, idealized.
OOC - Out Of Character. This can either refer to an OOC moment of a Character or refers to Player speaking and it's not a part of the game.
IC - In character.
Slash - Male Homosexuality (either it's acceptable or unacceptable)
Femslash - Female Homosexuality (see above)
Godmodding - Basically it's when a character does anything it wants without limits or boundaries. This is never allowed. Considered grounds for immediate rejection/disregard for anything in the game.
AU - Alt. Universe
Crack - Something intentionally stupid or funny for the sake of comedy
Metagaming - Bringing OOC knowledge to the IC game or something that the IC couldn't know but the OOC does and the IC states it.
Tagging - The concept of “marking” a thread as either open (available to all) or closed (meant for particular characters).
Canon - Original source material (from a game, manga, anime, TV show, movie) used in the game, same universe, etc. The players either RP OCs or official characters.
Fanon - Original source but mixed in with other elements created for the plot. May be AU or some sort of twist.
Genre - Drama, Comedy, Dark, AU, Family, Action, Adventure, Horror, etc.

More in-depth information can be found here and here.


GAME LITERACY

Amateur - Lowest level of literacy. It can be at least one sentence long. It can be just "talking" or just an action. It's short, typically. Doesn't involve massive typing. Just your basic RP. Not difficult.
Semi-Lit - The most common form of text-rpg. The minimum is at least one paragraph or 3 sentences. Excepts are made if the RPer just can't come up with anything else to say. So long as it isn't consistent, bending it is fine. Contains more than just basic action, it also is about describing things.
Lit (Literate) - The most advanced form. Typically involves at minimum 3 paragraphs worth of stuff but most go beyond that. Has a lot of description, be it of surroundings or what the character is feeling or doing. Typically, Lit RPs are strict about being lit and require a sample of writing before acceptance.